Effect of temperature and inoculum size on reproduction and development of Heterorhabditis heliothidis and Steinernema glaseri (Nematoda: Rhabditoidea) in Galleria mellonella

Abstract

Larvae of Galleria mellonella were kept at temperatures of 5, 10, 15, 20, 25, and 30 °C, and exposed to six levels of inocula (5, 10, 25, 50, 100, and 500 infective juveniles/larva) of Heterorhabditis heliothidis and Steinernema glaseri. Temperature and inoculum level significantly affected time to first emergence, duration of emergence, and yield of juveniles. All parameters except emergence of H. heliothidis showed significant interactions between temperature and inoculum level. No juveniles emerged at 5 or 10 °C and development time was most rapid at 25 °C. No juvenile H. heliothidis emerged at 30 °C or with 500 infective juveniles/host, but duration of emergence was shortest at high temperatures with large inocula; yield per host and yield per inoculum were greatest at 20 °C with small inocula. Yields of S. glaseri were half those of H. heliothidis; duration of emergence was shortest at low temperatures; yield per host was greatest at 20 and 25 °C from large inocula; and yield per inoculum level was greatest when the numbers inoculated were small (5–50/host).